board change questions

[ExArmy]

theoretical question:

if the main fuse is a 80A BS88 type IIb, tails are 25mm with 16mm earth, can i install a 10 way dual rcd board with a 100A main switch?

how is the total load calculated? all the MCB'sin your average 10 way bpard add up to way over 100A?

 

[ebow72]

Add all breaker sizes together then multiply by 0.4 for max demand, I think...
I have done this as a practical and seem to remember doing this.

 

[telectrix]

about right. 0.4. and @ exarmy. remember your 100A rating of your main sw. is just the max. current it can safely take. nbot as if it's an overload device.

 

[brman]

what is your diversity calculation?

EDIT: ok, beaten to it by ebow and tel.

 

[Paul.M]

Your 100A iso will trip before the 80A bs88 trust me, your not living on a prayer, just physics.

 

[ExArmy]

Your 100A iso will trip before the 80A bs88 trust me, your not living on a prayer, just physics.

really? i'd of thought the bs88 would trip eventually (120+ amps) but the main switch won't ever trip

 

[Jay Sparks]

Your 100A iso will trip before the 80A bs88 trust me, your not living on a prayer, just physics.

The iso will not trip, its not an overload device, its simply for isolation.
"believe" me! lol
(Cher)


Jay

 

[sjm]

BS 88 type IIB??
All domestic boards come with 100 amp main switch, not sure what your problem is!
Most, if not all domestic installations have breakers that add up to more than 100 amps. Common sense says that if you are not altering the installation to include extra loads then the main fuse will continue to be sufficient.

 

[Guitarist]

As Jay says, the isolator is not a "trip". Its rating must be equal to or higher than the main fuse, that's all.

 

[brman]

really? i'd of thought the bs88 would trip eventually (120+ amps) but the main switch won't ever trip

Ah, is that the reason for your 1st question? The 80A BS88 taking more than 100A to fuse so theoretically overloading the isolator?
I think the right answer to that one is - don't worry about it.

 

[Paul.M]

As Jay says, the isolator is not a "trip". Its rating must be equal to or higher than the main fuse, that's all.

@ Jay Sparks and Guitarist, yes your correct I didn't read the op fully.

My previous post let it burn (Usher )

 

[Paul.M]

@ Jay Sparks

What goes beep, beep beep, beep?

Man utd open top bus going back into the garage.

Sorry mate couldn't resist and I'm not a footy fan. Oh well every rose as a thorn, you might do better next season. You've got to live and let die in that game I'm afraid.

 

[telectrix]

who'd have an open top bus in manchester when it rains every day that's got a "y" in it?

 

[Jay Sparks]

@ Jay Sparks

What goes beep, beep beep, beep?

Man utd open top bus going back into the garage.


Sorry mate couldn't resist and I'm not a footy fan. Oh well every rose as a thorn, you might do better next season. You've got to live and let die in that game I'm afraid.

Bang Bang you shot me down, Bang Bang I hit the ground........
Harsh but fair.
I suppose in the end, "Every loser wins"

Jay

 

[brucelee]

mate its only 1 yr and only by a few goals always next year lets see if they can win it as many times as utd have and be as dominent
with the money city have utd would never lose lol